From what I have read ComicVine is just an one or two guys that manage the CV side of things, and the API is run by the same ones that run the gamespot api (probably one of the reasons why they merged everything under the gamespot url as they've always been under the gamespot umbrella). And from my understanding there is only one guy doing the Wednesday-new release type updates on CV, and if he's away/sick/on vacation things grind to a halt with updates which has a domino effect on a lot of things.

There was a time when you could get them to send you the entire offline CV db for usage - but I haven't actually seen the CV db itself. It would be neat to have that, and then just periodically update it with new information from CV (the rss feeds would work well). It could be done, but would require abit of work to get things working smoothly enough that it could be used as a reliable alternative to the actual CV.

As far as alternative API's - well, it's pretty simple, there isn't any. Comicvine is the only one that offers an API. GCD was supposed to roll out one a few years ago, which never happened, and it's since been said that they have zero intention of making one for public usage. So there's the 2 biggest 'general' collectors of comicbook information right there. Marvel and DC have API's that can be used, sure - although using either for this type of program would probably be crossing some boundaries at some point I'm sure.

The GCD stuff can be parsed directly but it runs into the typical issues when it comes to webpage parsing (if the layout change things will break, inconsistent results due to different structures, etc). When Mylar was first starting out, the CV API wasn't at the stage it's currently at and as such to get all the right amount of data, it has to use a combination of CV and GCD data. The main problem with it is trying to get both sets of data to line up correctly.